Biomedical Engineering Reference
In-Depth Information
The O
2
supplied is:
Moles of O
2
32
12
:
5
32
400 kg of O
2
=
min
3
5
3
5
From this, we can calculate:
ER
400
=
1848
:
75
0
:
22
5
5
15
The syngas constituents in the total product gas are CO (15.2%) and H
2
(42.3%). So, to produce 1000 N m
3
/min of syngas, the amount of product gas,
Q
pr
, is:
ER
5
280
=
1848
:
75
5
0
:
1739 N m
3
Q
pr
5
1000
=ð
0
:
152
1
0
:
423
Þ
5
=
min
The cross-sectional area of the gasifier reactor, A, is:
56 m
2
Assuming the operating temperature to be 1000
C and the pressure to be
25 bar, the volumetric flow-rate of product gas is:
4
2
A
5
π
=
4
12
:
5
1273
273
5
1
25
Q
0
pt
5
324 m
3
Q
pt
=
min
0.43 m/s.
The energy produced per N m
3
of product gas is found by multiplying the vol-
ume fraction by the heating value of each constituent, which is taken from
Table C.2 in Appendix C. Adding together the contribution of all product gas con-
stituents, gives the total heating value, HHV, as:
The space velocity of the gas flow V
g
is Q
0
pr
/A
324/(12.56
60)
5
3
5
HHV
0
:
004
25
:
1
0
:
152
0
:
152
3
ð
282
:
99
=
22
:
4
Þ
1
0
:
423
5
3
1
1
Nm
3
3
ð
285
:
84
=
22
:
4
Þ
1
0
:
086
3
ð
890
:
36
=
22
:
4
Þ
1
0
:
008
63
:
4
11
:
33MJ
=
3
5
Thus, the total energy produced, E
total,
is Q
pr
3
HHV
5
1739
3
11.33/60
5
328.3 MW
th
.
The hearth load is:
m
2
E
total
=
A
328
:
3
=
12
:
56
26
:
14 MW
=
5
5
8.6.3 Energy Balance
Unlike combustion reactions, most gasification reactions are endothermic.
Thus, heat must be supplied to the gasifier for these reactions to take place
at the designed temperature. In laboratory units, this is not an issue because
the heat is generally supplied externally. In commercial units, it is a major
issue, and it must be calculated and provided for. The amount of external
Search WWH ::
Custom Search